Macromolecular analytical ultracentrifugation has played key roles in the studies of biomedical researchers over the past decades. The development by Beckman Instruments of the new XL analytical ultracentrifuges and the concomitant development of exciting new experimental techniques and analysis procedures has sparked a renaissance in the application of analytical ultracentrifugation to contemporary questions in biomedical research. The XL analytical centrifuges combine enhanced experimental control and data collection with ease of use compared to the 1950s vintage Model E centrifuges that they supplant. For these reasons, the faculty of the Albert Einstein College of Medicine desire to acquire an XL-I analytical ultracentrifuge and are poised to make effective use of this instrument as a shared resource. Einstein possesses a strong community of structural biologists, biophysical chemists and molecular biologists whose research programs will benefit enormously by the information on macromolecular association that is accessible using the XL-I. The XL-I will be administered by the Laboratory for Macromolecular Analysis (LMA), a shared resource facility that has been providing state of the art analytical instrumentation to the Einstein faculty for the past decade. Several Einstein faculty participating in this application are experienced Model E jocks with the technical expertise to design and conduct experiments in analytical ultracentrifugation and a willingness to teach their colleagues and a new generation of scientists this elegant art.